Heating system for liquids



Aug. 18, 193 F. E. LICHTENTHAELER' HEATING SYSTEM FOR LIQUIDS Filed Oct. 22, 1927 2 Sheets-Sheet l 0/4 I/APOR C001. Sr/m/r Fig.2.

g F. E. LICHTENTHAELER HEATING SYSTEM FOR LIQUIDS Filed Oct. 22, 1927 2 Sheets-Sheet 2 P/PE Mxnma 1 g. 4 vE/v 727E.

Patented Aug. 18, 1931 UNITED STATES.

PATENT OFFICE HEATING SYSTEM FOR LIQUIDS Application filed October 22, 1927. Serial No. 227,974.

This invention relates to heating systems for use in vaporization processes such as the distillation of liquids, and more particularly to continuously operating systems employing tubes through which the liquid to be heated is forced at high velocity. In one of its aspects, the invention consists in a heating system in which heat is generated by surface combustion and utilized as radiant energy to raise the temperature of liquid circulated in tubes.

An im ortant application of the invention is to the distillation of petroleum or the like and the system of my invention is herein disclosed as constructed and arranged for use in this connection. v

- In another aspect, the invention consists in the further development and improvement of oil heating systems such as that disclosed in my prior application, Serial No. 225,462, filed October 11, 1927, wherein I have shown a system capable of handling oil at high velocity, with a minimum frictional resistance and at a relatively low pressure. The combustion of gases is accelerated by contact with hot surfaces and a very high percentage of the heat so evolved can be utilized in radiant form. Surface combustion is best accomplished by mixing gas and air in the proper proportions and burning the mixture in passing it through a porous mass of refractory material. This material acts as a catalyst within, or upon the surface of which, combustion takes place. If the refractory material is formed as a plate or shell, the gas mixture passes through it and burns upon its, further side, heating the material to incandescence to a depth of a few millimeters below its surface.

As already intimated, radiant heat is emitted with extreme intensity from one side of the refractory material while the outer side, from which the gas enters, remains comparatively cool. The object of my invention is to take advantage of the extremely favorable characteristics of surface combustion and provide a system in which, for the first time, its rinciples are utilized in heating a liquid sue as oil for vaporization processes. To this end, I provide a wall of refractory material adapted to. support surface combustion upon one surface and arranged to heat by radiant energy a tube or tubes throu h which the liquid is caused to flow at high ve ocity.

The invention will be best understood and appreciated from the following description of preferred embodiments thereof, selected for purposesof illustration and shown in the accompanying drawings, in which Fig. l illustrates the system more or less diagramatically Fig. 2 is a sectional view on the line 22 in Fig. 1;

Fig. 3 is a similar sectional view illustrating an alternative arrangement of the dil tubes; r

Fig. 4 is a view partly in elevation and partly in section of a heater embodying a single oil conduit; and

Fig. 5 is a cross sectional view of the same.

The heater comprises an outer shell or jacket 12 of sheet steel in the form of a vertically disposed cylinder with suitable heads at the top and bottom. Within the shell are supported two concentrically disposed cylinders of refractorymaterial, such as firebrick or alundum. The outer and larger cylinder 14 is spaced within the shell sufiiciently to leave an enveloping annular duct for the passage of the gaseous fuel mixture, which flows about the cylinder 14' and passes inwardly through its annular wall. The smaller cylinder 16 is centrally located and open at its lower end to ermit the entrance of the fuel mixture whic passes outwardly through its walls. The annular chamber formed between the two cylinders is closed at'the-lower end by an annular plate 18. The annular duct outside the cylinder 14 is closed at the upper end by a ring 20 and the upper end of the inner cylinder is closed by a plate 22.

The fuel mixture is supplied to the shell 12 through an inlet pipe 24, which enters the shell near its lower end after passing through a trap or seal 26, provided to eliminate the possibilityvof the combustion flashing back to the source of fuel supply. The products of combustion are taken from the shell 12 through the outlet pipe 30 leading from its upper end, and, while these are relatively cool, they can be utilized to advantage for preheating either the fuel mixture or the oil entering the system.

Oil is conducted to the system through the supply pipe 40 which leads to a centrifugal pump 42, from which the oil is forced to the inlet pipe 44 leading to a lower header 46.

A valve 41 in the pipe 40 controls the amount of oil admitted to the system. An annular series of tubes 48 is connected to the lower header 46 and at their upper ends to an upper header 50, having a discharge pipe 52 for conducting the hot oil and vapor out of the heater. The tubes 48, as will be seen, are equally spaced and disposed midway be tween the inner wall of the cylinder 14 and the outer wall of the cylinder 16, so that they are e ually subject to the radiant heat generated by surface combustion and emitted by these cylindrical surfaces. The header 50 is enclosed by heat insulating material 51 to reduce the heat loss at this point of the system.

Hot oil and vapor leaving the system by the discharge pipe 52 is led through a pipe 54 to a reservoir 56, having an outlet pipe 58 leading from its upper end to the fractionating tower, not shown. An oil pipe 60 1s located below the point at which the pipe 54 enters and serves to conduct hot oil to the fractionating tower and to determine the level of the hot oil in the reservoir. The reservoir 56 has also a recirculating connection, comprising the pipe 62 which leads back to the supply pipe 40 and through which the flow of recirculated oil may be controlled by a valve64.

In operation, gaseous fuel is admitted through the pipe 24 and is ignited at the inner surface of the cylinder 14 and the outer surface of the cylinder 16, as already explained. The material of the cylinders adjacent these surfaces is raised to incandescence and radiant heat emitted in great intensity to the vertical oil tubes 48. This heat is transferred with high efiiciency to the oil in the tubes and the products of combustion pass out of the system a relatively low temperature.

It is important in successfully operating a system of the character disclosed that the velocity of the oil in its path should be high. While the coeflicient of heat transfer in oil is low at best, this factor can be greatly improved by increasing the velocity of oil flow over the heated surface. It is, further, important to obviate the danger of local overheating, as this results in cracking the oil and in coking on the inner surfaces of the tubes. All of these conditions are favorably affected by a high velocity in the oil flow.

This is facilitated in the illustrated system by the'large number of short straight tubes arranged in parallel between the headers 46 and 50 and providing a relatively large effective cross sectional area. The system may be operated continuously without recirculation by closing the valve 64 if desired, or a proportion of the oil treated may be recirculated, depending upon the flow in the recirculating pipe 62 controlled by the valve 64.

In the alternative construction illustrated in Fig. 3, I have shown oil tubes 68'as arranged in staggered relation in two concentric circles, the tubes being somewhat smaller in diameter than those shown in Fig. 2. This maintains the same large effective cross sectional area for oil flow but provides for a different distribution of the heating surface, which may be found advantageous under some circumstances.

It will be noted that the tubes are so spaced and arranged within the chamber as not to shadow each other but to afford an unobstructed path for the radiant heat to all tube surfaces.

A modified formof heater is illustrated in Figs. 4 and 5, in which is employed a single conduit for the oil, comprising a tube of annular form. In this embodiment of the invention, a chamber having porous walls of refractory material is formed by the cylinders 114 and 116, located within the sheet m'etal shell 12. The oil conducting tube 148 is concentrically disposed in the chamber thus formed and supplied with cool oil through the intake pipe 144, which enters it tangentially. Oil entering at high velocity through the inlet pipe 144 will follow a more or less spiral path in the shell of the tube, finally leaving the tube by the outlet pipe 152, which leads tangentially from the tube at its upper end and through which the hot oil and vapor may be conducted to a reservoir and fractionating tower.

It will be seen that the annular shell of the tube 148 affords a free passage of large effective cross section for the oil through which the latter may pass at high velocity.

The surfaces of the tube 148 also afford extensive absorption area for the reception of the radiant heat of combustion received from the walls of the chamber. Gaseous fuel is admitted through the inlet pipe 124 to the space without the cylinder 114 and within the cylinder 116 and the products of combustion are discharged through the outlet pipe 130 at the upper end of the heater in a manner similar to that explained in connection with the heater of Fig. 1.

Having thus described my invention, what I claim is:

1. A'systcm for heating oil moving at high velocity through an annular container, comprising inner and outer cylindrical walls of porous refractory material positioned opposite the inner and outer sides of the container respectively and forming an annular heating chamber, and a duct for supplying gaseous fuel. to the walls of said chamber whereby to maintain surface combustion at their inner surfaces adjacent the container.

2. A system for heating oil moving at high velocity through a plurality of oil tubes spaced equally and in concentric design, comprising inner and outer cylindrical walls of refractory material forming an annular heating chamber that envelops the oil tubes, said walls being constructed so that their opposed concentric faces are capable of being maintained at incandescence to support surface combustion, a shell spaced from the outer wall of said annular chamber and forming therewith an enveloping duct for gaseous fuel, means to enclose the inner wall to form a gaseous fuel duct therein, and a discharge outlet for the products of combustion leading from said annular chamber.

3. A system for heating liquids flowing at high velocity in a container, comprising concentric shells of porous refractory material forming an annular chamber enveloping the container, means for maintaining a substantially uniform pressure of gaseous fuel without the outer shell and within the inner shell to support surface combustion upon the opposed surfaces thereof, and a duct for the products of combustion leading from the annular chamber.

4. A system for heating liquids flowing at a high velocity in a container, comprising concentric cylindrical shells of refractory material constructed to maintain surface combustion upon their opposed faces and disposed so as to form a chamber that envelops the container, and means for conducting gaseous fuel to the outer face of the outer shell and the inner face of the inner shell.

5. A heating system for liquids circulated at high velocity, comprising an outer casing forming a chamber, concentric cylinders of porous refractory material enclosed within said chamber, a liquid container disposed between said cylinders, and means for delivering gaseous fuel to said casing, both refractory cylinders beingspaced at their lower ends from the outer casing to permit the fuel to flow to the outer surface of the the outer cylinder and the inner surface of the inner cylinder.

FRANK E. LICHTENTHAELER. 

